Installing a
threshold on an exterior door is a crucial task for ensuring a weather-tight seal and smooth operation of the door. Thresholds (or sills) sit under your door, it helps in directing the water away from your home. The Threshold works together with a door sweep to seal the bottom of your entryway against pests and drafts.

This guide provides a step-by-step approach to removing the old threshold, preparing and installing a new one, and ensuring it is securely fitted. Whether you're a seasoned DIYer or a novice, these instructions will teach you how to install a threshold on an exterior door.

Key Takeaways

  • Ensure accurate measurements of the doorway to properly know how to install a threshold on an exterior door. 
  • Remove all debris and old caulk from the doorway area to prepare for a clean installation.
  • Test the fit of the new threshold before securing it to avoid any issues with door operation.
  • Use appropriate tools and materials, such as a hacksaw for cutting and adhesive for securing.
  • Regular maintenance and checks are necessary to sustain the threshold’s integrity and functionality.

Remove the Old Exterior Threshold

Unscrew and Lift Out the Old Threshold

    • Start by removing any rubber strips or seals on the existing threshold.
    • Unscrew the screws holding the threshold in place using the appropriate screwdriver.
    • Carefully lift out the old threshold, using a pry bar if necessary to dislodge it.
Clean the Doorway Area
    • Once the old threshold is removed, clean the area thoroughly.
    • Remove any debris, dust, or old caulk that might be present.
    • Ensure the surface is clean and dry before installing the new threshold.

Check for Damage

    • Inspect the doorway and the area where the old threshold was installed for any signs of damage before you take the next step of how to install a threshold on an exterior door. 
    • Look for rot, mold, or structural damage that might need repair before installing the new threshold.
    • Address any issues found to ensure a solid foundation for the new threshold.

Prepare the New Exterior Threshold

  • Measure the Doorway

Start by measuring the width of the doorway from one side of the door casing to the other. Ensure accuracy as this will determine the fit of the new threshold.

  • Cut the New Threshold to Size

Once you have your measurements, mark the new threshold accordingly. Use a saw to cut the threshold to the correct length, ensuring a clean and straight cut.

  • Clean and Prep the Area

Before installing the new threshold, clean the area thoroughly. Remove any debris, dust, or old caulk. This will help the new threshold adhere better and provide a cleaner finish.

Install the Exterior Threshold

  • Test the Fit

Before securing the new threshold, place it in the doorway to ensure a proper fit. Make any necessary adjustments, such as trimming the threshold further or sanding down high spots, to prevent the door from sticking.

  • Secure with Adhesive and Nails

Once the fit is confirmed, apply a bead of adhesive along the bottom of the threshold. Carefully position it back in place and secure it using nails or screws. Ensure that it is aligned straight and level for optimal performance.

  • Apply Finishing Touches

After installation, fill any gaps with caulk to create a weathertight seal. This not only improves the threshold's functionality but also enhances its appearance. Finally, check the door’s operation to ensure it opens and closes smoothly without any obstruction.

Securing the Exterior Threshold

  • Check for Stability

Ensure that the newly installed threshold does not move or budge when pressure is applied. Check for any movement and make sure it feels secure underfoot.

  • Adjust Door for Fit

If the door does not close smoothly over the threshold, adjustments may be necessary. You might need to plane the bottom of the door to achieve the perfect height and clearance.

  • Final Inspection

Conduct a thorough inspection to ensure everything is properly aligned and secure. Look for gaps or areas that may need additional sealing to protect against weather and moisture.

Tools and Materials Needed

  • Hammer
  • Block of wood
  • Drill
  • Hacksaw
  • Chisel

List of Required Materials

  • Flooring adhesive
  • 10d casing nails
  • Exterior wood putty
  • 12d casing nails
  • Sill cover (optional)

Preparation of Work Area

Ensure the work area is clean and free of debris before beginning the steps of how to install a threshold on an exterior door. This will help in achieving a smooth and efficient installation process.

Additional Tips for Installing a Threshold

  • Handling Metal Thresholds

When installing a metal threshold, use appropriate tools such as tin snips and a metal-cutting blade. Ensure all cuts are precise to avoid any gaps or misalignments.

  • Weatherproofing Considerations

To weatherproof and protect your threshold from outer elements, apply a silicone caulk around the edges. This not only secures the threshold but also prevents water and air leakage.

  • Maintenance Tips

Regular maintenance is crucial for the longevity of your threshold. Check periodically for any signs of wear or damage and address them promptly to maintain its functionality and appearance.

Troubleshooting Common Installation Issues

  • Door Not Closing Properly

If the door does not close properly after installing the threshold, check the alignment and make sure there are no obstructions. Adjust the threshold if necessary to ensure a smooth operation of the door.

  • Threshold Not Fitting

Ensure that the measurements were accurate and the threshold was cut precisely. If gaps are present, consider using shims or re-cutting the threshold for a better threshold installation. 

  • Adhesive Issues

For adhesive failures, ensure the surface was clean and dry before application. Use a recommended adhesive for exterior thresholds and apply it evenly. Allow sufficient drying time as per the product instructions.


Knowing how to install a threshold on an exterior door is a practical project that enhances your home's energy efficiency and weather resistance. By following the steps outlined in this guide, from removing the old threshold to securing the new one, you can ensure a snug and proper fit that will stand the test of time. Remember to measure carefully, cut precisely, and secure firmly. With the right tools and a bit of patience, you can successfully install a threshold and improve the functionality and appearance of your exterior door.

Frequently Asked Questions

1. How do I remove the old exterior threshold?
Start by removing the rubber strip on the existing threshold, then unscrew the screws holding it in place and lift out the old threshold.

2. What should I do to prepare the new exterior threshold?
Measure the doorway to ensure a good fit, cut the new threshold to size using a hacksaw, and clean the area of any debris or remaining caulk.

3. How do I install the new exterior threshold?
Test the fit of the threshold, apply flooring adhesive, place the threshold, drill pilot holes, and secure it with nails. Fill any nail holes with exterior wood putty.

4. What should I check during the final inspection?
Ensure the threshold is stable and secure, and that the door closes comfortably without obstructions.

5. What tools and materials will I need?
You will need a hammer, block of wood, drill, hacksaw, chisel, flooring adhesive, nails, and exterior wood putty.

6. What are some additional tips for installing a threshold?
If replacing with a metal threshold, consider cutting the stop moldings to fit around it. Protect your floors with a drop cloth during installation.
    May 10, 2024 — David Pease

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